LED lighting equipment is well known to the public. In LED lighting equipment, for example, an LED module is mounted on a substrate and an LED package constituting a substrate in which an LED chip is enclosed is used. In the LED module and in the LED package, power to the LED chip is compulsory.
Conventionally, a known technology is disclosed in JP 2009-99627 A, wherein an input terminal of an LED mounted substrate connects to an output terminal of an AC-DC converter connected to a commercial power supply using a lead wire, to power the LED chip. In the technology disclosed in JP 2009-99627 A, the lead wire is directly soldered to the input terminal of the LED mounted substrate.
It is disclosed in JP 2006-114791 A an LED connector having a socket contact to elastically contact a terminal of an LED chip, the socket contact having a wire connecting section where the socket contact connects an electric wire connected to a power supply, for energizing the LED chip. In the socket contact, the electrical wire is connected to the wire connecting section by crimping.
Furthermore, it is shown in FIG. 8 (see JP 2010-514138 A) a known low-profile surface mount push-in connector to power the LED chip.
The known push-in connector shown in FIG. 8 is composed of an insulating housing 110 shown in FIG. 8A and two contacts 120 shown in FIG. 8B, which are received in the housing 110. The push-in connector is mounted, for example, on a substrate 40 on which an LED module is mounted (see FIG. 4), or on a substrate 62 made up of an LED package (see FIG. 6).
Herein, the housing 110 is made by molding insulating resin, on the front (the left side in FIG. 8A) of which two openings 111 for inserting an electrical wire are formed. The electrical wire (not shown) is connected to a power supply.
Further, each contact 120 has a cylindrical small-diameter portion 121 and a cylindrical large-diameter portion 122 connected to the front end of the small-diameter portion 121 as shown in FIG. 8B. The each contact 120 is made by stamping and forming a metal plate. On a bottom wall of the large-diameter portion 122, a lance 123 is provided, which is cut from, bent, and extends diagonally from the bottom wall toward the inside of the small-diameter portion 121. At the tip of the lance 123, a sharp edge 124 is formed. The electrical wire is inserted into the large-diameter portion 122 through the opening 111 of the housing 110 while being guided thereto, but the tip of a covering portion of the electrical wire abuts against a shoulder 122a formed in the large-diameter portion 122 to prevent further insertion of the electrical wire. Upon slightly pulling out the electrical wire, the sharp edge 124 formed on the tip of the lance 123 bites into a wire core projected from the front end of the covering portion of the electrical wire for connecting the electrical wire to the contact 120, and stopping the electrical wire from removal. Thus, a contact which can be connected to the electrical wire by merely inserting the electrical wire into the contact is generally called as a push-in contact.
Moreover, at the front end (the left side shown in FIG. 8B) of the large-diameter portion 122, a surface mount soldering portion 125 is provided. The surface mount soldering portion 125 extends forward along an axial direction of the contact 120 from the bottom of the front end of the large-diameter portion 122. On the other hand, a surface mount soldering portion 126 is positioned at the rear end of the small-diameter portion 122. The surface mount soldering portion 126 extends backward along an axial direction of the contact 120 from the bottom of the rear end of the small-diameter portion 121. These surface mount soldering portions 125,126 are solder connected, for example, to the substrate 40 on which the LED module is mounted, or to a conductive pad formed on the substrate 62 made up of the LED package. The conductive pad is electrically connected to an electrode of the LED chip, which electrically connects the electrical wire with the electrode of the LED chip, enabling power to an LED.
These conventional prior art teachings, however, have problems as will be shown below.
Namely, in case of the technology disclosed in JP 2009-99627 A, the lead wire is directly solder connected to the input terminal of the LED mounted substrate. Therefore, the technology requires additional labor to wire the electrical wire to the input terminal and to solder the wire core of the electrical wire carried on to the input terminal. As a result, the process provides poor assembly and inefficiency.
Furthermore, in the technology disclosed in JP 2006-114791 A, the electrical wire is connected to the electrical wire connecting section of the socket contact by crimping. Therefore, additional work is required in wiring the electrical wire to the electrical wire connecting section of the socket contact and crimping the end of the electrical wire carried on to the electrical wire connecting section using a crimping tool, which leads to inefficiency.
Meanwhile, in case of the low-profile surface mount push-in connector disclosed in JP 2010-514138 A shown in FIG. 8, amelioration of workability of connection of the electrical wire, and assembly working efficiency may be achieved as well, due to the adoption of the push-in contact.
Nevertheless, in the low-profile surface mount push-in connector disclosed in JP 2010-514138 A, the large-diameter portion 122 to guide the tip of the covering portion of the electrical wire to the contact 120 is provided, and the large-diameter portion 122 is positioned with the shoulder 122a to stop insertion of the tip of the covering portion of the electrical wire. Accordingly, enlargement of the contact 120 occurs by the presence of the large-diameter portion 122. It follows, in addition thereto, that enlargement of the push-in connector in which the contact 120 is received occurs. Thus, the enlarged contact 120 and the push-in connector create a situation where light emitted from the LED is blocked by the connector, providing degradation of, so-called, light distribution characteristics.
Moreover, in case of the low-profile surface mount push-in connector disclosed in JP 2010-514138 A, the surface mount soldering portion 125 of the contact 120 extends forward along an axial direction of the contact 120 from the front end of the large-diameter portion 122. Further, the surface mount soldering portion 126 extends backward along an axial direction of the contact 120 from the rear end of the small-diameter portion 121. Therefore, the dimensions of the contact 120 are long in the axial direction, which induces enlargement of the contact 120. This also gives rise to enlargement of the connector, and consequently creates degradation of, so-called, light distribution characteristics.
Occasionally, a situation arises where the axial length of contact 120 is too long, which precludes mounting of the contact 120 on a small-sized substrate. In addition, a large surface mounting area of the contact 120 requires the distance (creepage distance) from a heat radiation plate (heat sink) disposed on the back side of the substrate to the substrate to be lengthened, where the LED module is mounted and to which the surface mount soldering portions 125,126 are soldered, or to the conductive pad formed on the substrate as the LED package. Thus, there has been a need to make the size of the substrate itself larger. Nonetheless, it would not be appropriate since making the size of the substrate larger runs counter to a customer's demand for downsizing of the substrate. Further, in cases where the contact 120 and the heat radiation plate are positioned on the back side of the substrate, the large mounting area of the contact 120 introduces a problem that a region of the heat radiation plate is smaller, causing degradation of heat radiation characteristics.